This application is related to two U.S. applications having Ser. No. 513,610 Now U.S. Pat. No. 4,486,858 and Ser. No. 513,657, both filed July 14, 1983, which are assigned to the Assignee of the present application.
1. Field of the Invention
The present invention relates to a magnetic bubble memory device which is used as a memory device for an electronic computer or for a terminal device of the same. More particularly, the present invention relates to the construction of a gate which operably associates a major line with a minor loop in a major-minor looporganized magnetic bubble memory device.
2. Description of the Prior Art
There is a well-known magnetic bubble memory device which comprises a thin layer of magnetic material in which magnetic bubbles can propagate along propagation paths in response to a magnetic drive field rotating or reorienting cyclically in the plane of the magnetic layer. One of the most common arrangements of the propagation paths for magnetic bubble memory devices is a major-minor loop organization. This organization includes a plurality of minor loops for the storage of bubble information and one or two major lines, or loops, for the propagation of bubble information between a bubble generator and the minor loops, and between the minor loops and a bubble detector. The major line or lines and the minor loops are operably associated with each other through gates which perform various functions, such as the transfer, replication, or swapping of bubbles, whereby the writing and the reading of bubble information between the major line or lines and the minor loops are performed.
There are two well-known types of propagation paths, one being defined by elements or patterns of magnetically soft material such as permalloy and commonly referred to as a "permalloy propagation path" and the other being defined by an ion-implanted pattern and commonly referred to as an "ion-implanted propagation path". It is well known in the art that in the case of forming a propogation path having the same bit period, the minimum geometric size required for forming an ion-implanted propagation path is larger than that required for forming a permalloy propagation path, and, accordingly, an ion-implanted propagation path is a very promising means for providing a high-density storage magnetic bubble memory device in which the bit period is 4 .mu.m or less and the memory capacity is 4 Mbit or more.
However, in a major-minor loop-organized magnetic bubble memory device employing an ion-implanted propagation path, it is very difficult to provide gates having superior operating margins, as is well known in the art.